An investigation of the ecology of the map turtle, Graptemys geographica (Le Sueur), in the northern part of its range

Abstract

Data obtained during the course of a 3-year study on a population of map turtles, Graptemys geographica, in Lac des Deux Montagnes, Quebec, Canada, suggest that the population size is approximately 351 turtles, that the sex composition is biased in favour of males, and that juveniles compose at least 8% of the total population. Map turtles emerge soon after ice breakup. During the prenesting period, males exhibit less movement over shorter distances than do females. In mid-May, female turtles start to move into the two bays used for nesting. The nesting season is about 2 weeks in duration, commencing in mid-June. The mean size of three clutches was 12. After nesting there appears to be a marked dispersal of both male and female turtles, with females moving more frequently and greater distances than males. By September the turtles have returned to the bays in the study area and remain until freeze-up. Bay utilization by the turtles is discussed in terms of food resources and human recreational use.